1. Field of the Invention
The present invention relates to a device for controllable dispensing of active substance, such as a chemical substance, a medication, a drug, or the like, to a person or other mammal, and more particularly, the invention is related to a portable device usable for transdermal and subcutaneous drug delivery or compound delivery in a programmable, automated, and/or controllable manner including control of the dose and timing of delivery to the patient. The invention further relates to the controllable stopping of compound delivery to the body. The invention further relates to the field of chronobiology in that the invention systems can be designed to modulate active agent delivery in accordance with biological rhythms pursuant to automated and/or pre-programmed dosage profiles. Bioactive substances are delivered transdermally into a body in a manner that is synchronized with biological processes and/or biological rhythms, and/or narcotic or other addiction cycles or other intra body or externally desired cycles so as to improve performance of the substance in the body or otherwise achieve a desired result by controlling blood plasma concentrations of a compound. The invention also relates to overcoming active agent tolerance, which may be experienced from continuous administration, overcoming active agent skin irritation, which may be experienced from continuous administration by allowing skin rest periods, improve patient compliance, and in some cases reducing the amount of drug needed per dose due to advantages of biosynchronization or programmed dosing. A programmable heating element may also be utilized to automatically heat the skin at precise times or intervals to assist in permeation and/or aid in the stopping of dosing.
2. Relevant Background
Medications provide effective treatments for a variety of illnesses. It is often preferred that medication is applied at a certain time or with a certain time pattern and in a manner that keeps the concentration of medication at a certain value to achieve a desired therapeutic result most efficiently. There are some medications that are only able to release effective pharmaceutical substances over a long period of time. Further, there are effective substances that are partially or totally inactivated following oral ingestion by the highly acidic environment of the stomach or by the filter impact of the liver. In order to overcome such problems, drugs are administered by either by transdermal delivery through the skin (e.g., with a patch) or subcutaneously with a needle or continuously by drip, with these later two methods being common parenteral methods for drug delivery. For a long-term treatment, the parenteral methods may be uncomfortable for the patient because of the repeated injury by needle injections and the limited liberty of action due to intravenous drip apparatus.
Patches are a form of transdermal drug delivery that is applied on the surface of the skin. These patches are capturing more and more attention in recent years because they are portable, comfortable, and suitable for patients with drug delivery in continuous dosages over a relatively long period of time without requiring active participation of the patient.
In the last decade, portable dispensing systems have been developed to provide a more flexible, precise and complex administration of drugs. Generally, the dispensing systems comprise a reservoir for a drug, a dispensing unit, and a patch (or a membrane that is permeable to the active substance, drug, or the like but relatively impermeable to a solvent in which the active substance is mixed in the reservoir). The reservoir through the dispensing unit is interconnected to the patch. The dispensing unit controls the releasing of the drug in the reservoir to the patch. The efficiency for patch transdermal drug delivery depends mainly on the diffusion rate of the effective substances through the skin. Maintenance of the concentration of the effective substances on the patch is essential to achieve the desirable diffusion rate. However, it has proven problematic to effectively control the concentration of substances on the patch in an effective manner. Further, it has proven difficult to provide an inexpensive portable device that allows a user or patient to easily refill the reservoir and to otherwise maintain the device.
In the field of drug delivery, it is recognized that supplying the drug in a correct temporal pattern is an important attribute of any drug delivery methodology. Controlled release drug delivery systems are intended to improve the response to a drug and/or lessen side effects of a drug. The recurring interest in chronopharmacology demonstrates the fact that biological rhythms are an important aspect of clinical pharmacology and should be taken into account when evaluating drug delivery systems (Hrushesky, W., J. Cont. Rel. 19:363 (1992), Lemmer, B., Adv. Drug Del. Rev. 6:19 (1991), Youn, C. B. J. Cont. Rel. 98 (3) 337 (2004) and Youn, C. B. J., Ed., “Chronopharmaceutics,” John Wiley & Sons, New York.
The onset and symptoms of diseases such as asthma attacks, coronary infarction, angina pectoris, stroke and ventricular tachycardia are circadian phase dependent. In addition, certain addictions (such as cigarette smoking) have times of day based on a persons circadian rhythms when symptoms peak. In humans, variations during the 24 h day in pharmacokinetics (chrono-pharmacokinetics) have been shown for cardiovascular active drugs (propranolol, nifedipine, verapamil, enalapril, isosorbide 5-mononitrate and digoxin), anti-asthmatics (theophylline and terbutaline), anti-cancer drugs, psychotropics, analgesics, local anesthetics and antibiotics, to mention but a few. Even more drugs have been shown to display significant variations in their effects throughout the day (chronopharmacodynamics and chronotoxicology) even after chronic application or constant infusion (Ohdo, S. Drug Safety 26 (14) 999-1010 (2003)). Moreover, there is clear evidence that dose/concentration-response relationships can be significantly modified based on the time of day. Thus, circadian time has to be taken into account as an important variable influencing a drug's pharmacokinetics and its effects or side-effects (Bruguerolle, B., Clin. Pharmacokinet. August 35 (2) 83-94 (1998)).
Studies indicate that the onset of certain diseases show strong circadian temporal dependency. This has led to the need for timed patterning of drug delivery as opposed to constant drug release (Lemmer B., Ciba Found Symp. 183: 235-47; discussion 247-53 (1995). The term “controlled release” refers generally to delivery mechanisms that make an active ingredient available to the biological system of a host in a manner that supplies the drug according to a desired temporal pattern. Controlled release drug delivery systems may be implemented using: a) instantaneous release systems; b) delayed release systems, and c) sustained release systems. In most cases, controlled release systems are designed to maintain a sustained plasma level of an active ingredient in a drug within a human or animal host over a period of time.
Instantaneous release refers to systems that make the active ingredient available immediately after administration to the biosystem of the host. Instantaneous release systems include continuous or pulsed intravenous infusion or injections. Such systems provide a great deal of control because administration can be both instantaneously started and stopped and the delivery rate can be controlled with great precision. However, the administration is undesirably invasive as they involve administration via a puncture needle or catheter.
Delayed release refers to systems in which the active ingredient made available to the host at some time after administration. Such systems include oral as well as injectable drugs in which the active ingredient is coated or en-capsulated with a substance that dissolves at a known rate so as to release the active ingredient after the delay. Unfortunately, it is often difficult to control the degradation of the coating or encapsulant after administration and the actual performance will vary from patient to patient.
Sustained Release generally refers to release of active ingredient such that the level of active ingredient available to the host is maintained at some level over a period of time. Like delayed release systems, sustained release systems are difficult to control and exhibit variability from patient to patient. Due to the adsorption through the gastrointestinal tract, drug concentrations rise quickly in the body when taking a pill, but the decrease is dependent on excretion and metabolism, which cannot be controlled. In addition, the adsorption through the gastrointestinal tract in many cases leads to considerable side effects (such as ulcers), and can severely damage the liver.
Transdermal therapeutic systems (TTS) have been developed primarily for sustained release of drugs in situations where oral sustained release systems are inadequate. In some cases, drugs cannot be effectively administered orally because the active ingredients are destroyed or altered by the gastrointestinal system. In other cases the drug may be physically or chemically incompatible with the coatings and/or chelating agents used to implement sustained release. In other cases a transdermal delivery system may provide sustained release over a period of days or weeks whereas orally administered drugs may offer sustained performance over only a few hours. A wide variety of active substances can be delivered through transdermal systems so long as the active substance can be provided in a form that can cross the skin barrier, see for example, U.S. Pat. No. 6,638,528, which is incorporated herein by reference.
In most cases transdermal delivery systems are passive, taking the form of a patch that is attached to the skin by an adhesive. The TTS includes a quantity of the active substance, along with a suitable carrier if need be, in a reservoir, matrix or in the adhesive itself. Once applied, the active ingredient diffuses through the skin at a rate determined by the concentration of the active substance and the diffusivity of the active substance. However, a variety of physical and chemical processes at the skin/patch boundary affect the delivery rate and may eventually inhibit drug delivery altogether.
The original performance target for controlled drug delivery is to achieve a zero-order release rate of the drug, so that a constant efficacious drug concentration is maintained in the blood plasma. However, more than two decades of research in chronobiology and chronopharmacology have demonstrated the importance of biological rhythms to the dosing of medications as well as determine the influence of a patient's circadian or other biological rhythms on drug efficacy and efficiency. This research reveals that certain disease symptoms follow a daily pattern, with peak symptoms at certain times of the day. It has been widely acknowledged that hormones, neurotransmitters and other intra-body compounds are released in different amounts at different times of the day pursuant to daily patterns.
The new approach stems from a growing body of research that demonstrates that certain diseases tend to get worse at certain times of the day. Also, certain disease symptoms have peak periods when cravings are at their highest. By synchronizing medications with a patient's body clock, and/or addiction cycles, many physicians believe that the drugs will work more effectively and with fewer side effects. In some cases, the improvements have been so pronounced that doctors have been able to reduce dosages. Circadian physiologic processes have been found to alter drug absorption, distribution, metabolism, and excretion. As a result, drug doses need to be adjusted to meet the differing needs of target organs or tissues at various times of the day (see, L. Lamberg, American Pharmacy, N831 (11): 20-23 (1991)).
The continued interest in chronopharmacology shows the ever-increasing need to develop technologies to control the temporal profile in drug delivery. Research findings suggest that the onset and severity of many diseases are cyclic in nature, or follow circadian patterns. Addiction symptoms also show cyclical nature. For example, cigarette smokers experience peak nicotine cravings upon waking, but nicotine is a stimulant, so there is a clear advantage to have an automated drug delivery system that can be programmed to not release nicotine during the sleep cycle, but to release nicotine prior to waking, because this would effectively combat peak morning nicotine cravings while removing the adverse side effect of sleep cycle nicotine disturbances. Drug tolerance adds to the need for modulation of drug dosing profiles. Additionally, skin irritation and sensitization caused by medications may require intervals during which no drug is administered. For example, fentanyl when administered continuously without rest periods can cause severe skin irritation, so there is a clear advantage of allowing the skin a “rest period” when no fentanyl is delivered in order to decrease adverse skin irritation and give the skin a chance to recover. Therefore, this improved form of drug delivery will be very important to people who need medicine easily, painlessly and automatically delivered to their bodies in timed increments (see Smolensk, M. H. & Lamberg, L. Body Clock Guide to Better Health. How to Use Your Body's Natural Clock to Fight Illness and Achieve Maximum Health, Henry Holt & Company, New York (2001) and Grimes, J. et al., J Pharmacol Exp Ther 285 (2): 457-463 (1998)).
Active transdermal delivery systems have been developed to help regulate the delivery rate by providing mechanisms to improve drug delivery over time by “pumping” the active ingredient. One such system, (U.S. Pat. No. 5,370,635), describes a system for delivering a medicament and dispensing it to an organism for a relatively long period of time, for example at least a few days. The device can be adapted for positioning on the surface of the skin of a human or possibly an animal body in order to apply a medicament thereto from the outer side thereof. Conventional transdermal systems circumvent the disadvantages of the adsorption through the gastrointestinal tract, but they do not optimize or tailor the dosing regiment to offset peak symptoms. In addition the constant transdermal delivery of a drug can lead to severe side effects, including debilitating sleep disorders (if the drug is a stimulant) and ever increasing tolerance (such as pain medications).
A simple type of transdermal chronotherapy is a biphasic profile, in which the drug concentration changes from a high to a low level (or vice versa) over time. Although the system can be physically applied or removed to alter the drug level, patient compliance with this procedure may be difficult, particularly during inconvenient hours. To generate a biphasic profile, the delivery system may utilize an external regulator, as described in Fallon et al. (U.S. Pat. No. 5,352,456) which illustrates a device for drug administration through intact skin that provides an initial pulse in the flux of the drug through the skin followed by a substantially lower flux of drug through the skin. Additionally, Fallon et al. (U.S. Pat. No. 5,820,875) later describe a device for the administration of a drug through an area of intact skin over a period of time in which the flux of the drug through the skin varies temporally in a controlled manner; The device is such that the skin flux of the drug varies in a controlled manner over the period of administration, typically from a high flux in the initial stage of administration to a lower flux in the later stage of administration.
Transdermal temporally controlled drug delivery systems, proposed by Giannos et al. (U.S. Pat. No. 6,068,853) coupled pH oscillators with membrane diffusion in order to generate a periodic release of a drug or active ingredient transdermally, without external power sources and/or electronic controllers. The intent was to address chronotherapy with a pulsatile transdermal system. The strategy was based on the observation that a drug may be rendered charged or uncharged relative to its pKa value. Since only the uncharged form of a drug can permeate across lipophilic membranes, including the skin, a periodic delivery profile may be obtained by oscillating the pH of the drug solution (see Giannos, S. A., “Pulsatile Delivery of Drugs and Topical Actives,” in “Novel Topical Actives and Delivery Systems: Cosmetics, Dermatologicals and Transdermals”, Edited by John. J. Wille, Jr.: Blackwell Publishing, Oxford UK (In press)).
Recently, an orally administered drug for arthritis treatment has suggested a chronotherapeutic approach using a delay release system. The delay is scheduled to release the active ingredient at the beginning of an interleukin 6 cascade that is believed to cause early morning stiffness in rheumatoid arthritis patients. By attempting to synchronize the drug delivery with a biological cycle it is believed that low doses may be used to achieve desired results. However, this system does not overcome the limitations of delayed release systems described above.
Although it may possible to meet the requirements of chronopharmacology with pills, this requires an enormous amount of discipline by the patient to comply with the treatment regiment, see for example, U.S. Pat. No. 6,214,379, which is incorporated herein by reference. As illustrated earlier, to achieve optimal results, many patients may need to wake up during the night to take their medication. Hence, what is needed is a non-invasive, reliable means of delivering drugs compounds in precisely timed and measured doses-without the inconvenience and hazard of injection, yet with improved performance as compared to orally delivered drugs.
Addressing patient compliance (taking the proper dosages at the prescribed times) is another critical problem facing caregivers and pharmaceutical firms alike. Studies show that only about half of patients take medications at the times and in the dosages directed by their physician. It is reported that each year, 125,000 deaths and up to 20% of all hospital and nursing home admissions result from patient noncompliance. It is estimated that non-compliance results in additional healthcare costs in excess of $100 billion per year in United States. These figures are even more pronounced for the elderly.
An individual's failure to comply with a dosing regimen, e.g. failure to take one or more doses of a drug or taking too many doses, will have an adverse impact upon the success of the regimen. Individuals may fail to comply with their drug dosing regimen for a number of reasons. For example, drug dosing regimens, such as every 4 hours, e.g., 8, 12, 4, 8, 12, and 4 and the like, involve a rigid dosing schedule that may be incompatible with an individual's personal schedule. Such a rigid dosing schedule when combined with normal human traits such as forgetfulness or denial of a medical condition, as well as a busy life, represent substantial obstacles to compliance with a drug dosing regimen. Accordingly, such rigid dosing regimens often result in the failure by an individual to take one or more doses at the prescribed time. This has an adverse impact on the levels of the therapeutic substance at the active site and consequently on the overall efficacy of the therapeutic substance.
Hence, a need exists for systems and methods that increase patient compliance for administration of a variety of drugs. Also, there remains a need for an improved patch-based (or membrane-based) delivery system for an active substance that is able to administrate the delivery of a chemical substance to a subject over a period of time in a controllable way. It is a preferable for such a system or device to administrate the delivery of a chemical substance in a pulsatile and scheduled manner, pursuant to a pre-programmed dosage delivery regimen, meaning dosage sizes and times can be automatically varied according to such pre-programming.